Too much watering?

Hello,

We have a Pieris in a pot, which has really come on this year. But over the past week or so, we've noticed that some leaves are starting to yellow. On line research suggests that one such reason can be over/under watering.

Now my other half ventures into the garden daily, with a moisture reader and checks levels. This plant is often dry, so she waters it. I think that this may be too much and that it's natural for a plant to experience dry soil every now and again. But I'm no expert.

Am I correct in that assumption? Is it possible to over water a plant, even if in a pot with good drainage? What would you recommend? And if you had this plant, and saw these yellow leaves, what would you do to address it?

 

I’d give it a bigger pot.

 

It may benefit from a dose of sequestered iron too which can remedy yellowing leaves.

 

I agree, a bigger pot with ericaceous compost plus topsoil and some potting grit would be good for it. Yellowing leaves could be the result of imperfect watering but they could also be a sign of a nutrient deficiency. The plant might have used the nutrients in that compost, plus erricaceous compost tends to lose its acidity over time.

 

When watering shrubs in pots, it's best to give them a thorough soaking until the water runs out of the drainage hole then let the top couple of inches dry out before watering again.

Underwatering and overwatering can produce similar symptoms of yellowing leaves. If you can, raise your plant out of its pot to check whether the rootball is too dry or too wet. It definitely needs a larger pot and fresh soil based ericaceous compost.

 

Regarding frequency of watering, plants generally do benefit from a dry-wet cycle (without getting to bone-dry). A bigger pot should help with reducing the need for overly frequent watering, aside from the benefit of nutrition et cetera. Make sure to have some topsoil in there; I've seen shrubs struggle badly in pots if they are planted in nothing but compost.

 

Thank you for the responses so far. We shall get a bigger pot and follow the suggestions said so far. Forgive the silly question, but when it grows to fit the bigger pot, will this likely happen again? Will we just have to keep getting bigger pots? Or is it okay to cut it back?

 

Think, for a moment, of a plant as a human being. When a human being is a child it needs small clothes. As it gets older, it needs larger clothes. There comes a time when, over eating notwithstanding, the clothes size remains the same. The difference is that plants use their roots to find food and water, but the idea is the same. Give a child a small plate and a little cup and it will be happy. But an adult needs bigger dishes and larger cups and glasses.

Cutting bits off your old uncle Tom won’t change his need for two pints of Guinness and a meat pie. No, cutting the top part of the plant back will not help you get out of having to repot it. In fact, it might even make matters worse.

 

I tend to agree that there is some Chlorosis going on, repotting into a bigger pot will solve the problem short term.
But I'd not repot now, I'd wait until around early March, and in the meantime go down the Sequestered iron route.

 

@Tidemark I agree, but..
You can do things with plants that you can't with people.
Bonsai being an example.

You can keep it smaller overall by pruning the roots as well as the stems.
Its best to have a bigger pot, but if needs must...

 

There were a few bonsai children in my primary school. Deprived of sufficient food and coming from families with a dozen children they were never going to grow into proper sized adults. Rickets. Who sees rickets these days? Lots of people with short bandy legs in my youth.

 

I think the big difference between plants and people are people grow to a certain size and then pretty much stop, height wise anyway, but plants usually continue to grow throughout their life, often much slower, but they rarely stop entirely until they die.

 

@Pete8 said ]......big difference between plants and people are people grow to a certain size and then pretty much stop, height wise anyway,........ and then start going the other way!]







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It's hard to overwater Pieris if the drainage and growing medium suit it @Scruffbag . Is there a reason you don't have it in the ground? Many people feel they can't have them if the soil isn't acidic, but they're perfectly happy in neutral soil if it's not at the alkaline end of neutral.
The bigger pot will help, but make sure you use a soil based medium for it - not just compost. That's no use if it's staying potted. I disagree about waiting to repot - you can do it now, assuming the conditions you have are suitable.
You can also prune them no bother, rather than finding bigger and bigger pots, but wait until the spring/early summer new foliage has changed to the normal colour. It's part of the attraction. Root pruning would probably need doing too, as the rootball will gradually take over and leave it lacking in sustenance. They'll stay quite happily in pots long term, but you'll always find a bit more dead foliage in a potted specimen than when they're in the ground.

 

The other issue with pots is it can be moist top and bottom but dry in the middle. This is common especially with peat free composts.
We were planting Nandina domestica at Capel (where I volunteer) recently. They were good size plants in decent pots. One of the Apprentice gardeners had been watering them for us in the days before we were due to plant. I'm sure he thought he'd been thorough, when we knocked them out of the pots they were exactly as I described, we had to soak them in a bucket for 10-15 mins before we planted.